The diagnosis of multiple sclerosis (MS), just as that of most other neurologic disorders, is based primarily on the neurologic history, findings on neurologic examination and, lesser extent, results of special examinations. Since the initial delineation of MS as a distinct clinical and pathologic entity by Charcot in the past century, the diagnosis has been based on symptoms and objective evidence of white matter lesions of the central nervous system disseminated both temporally and spatially, with onset for all patients is in the second half of the third decade of life. The disease has a peculiar geographic distribution, being more prevalent in northern, temperate latitudes and less frequent in tropical and subtropical regions of the world. Epidemiologic studies of MS make this disease compatible with genetic as well as with a variety of known and unknown environmental etiologic factors, and the current pathogenetic hypothesis suggests a significant dysregulation of immunologic mechanisms, probably triggered by a viral exposure early in life. It should be pointed out that as of now no single virus has yet been identified as the most likely culprit.
Disturbances of sensation, motor disorders, gait difficulties and monocular loss of vision are the most common symptoms in multiple sclerosis at the time of initial examination, to the point that in their absence, and in the absence of a clear course of remissions and exacerbation, and in the presence of an entirely normal cerebrospinal fluid examination, the diagnosis of MS should be considered at least doubtful. The combination of symptoms and sign in established case can be quite varied and can mimic any syndrome attributable to central nervous system white matter disease. Symptoms and signs attributable to gray matter disease, such as seizures, aphasia, apraxia etc. are quite unusual, at least initially.
Although the diagnosis of MS is ultimately a clinical one, advances in laboratory, neurophysiologic and neuroimaging techniques have aided in the diagnosis of this disorder. At the current stage of our knowledge, however, no diagnostic test can be considered 100% specific.
Approximately 75% of all patient manifest a course of the disease characterized by remissions and exacerbations and approximately 25% have a chronically progressive course from the very onset of the disease. A very small percentage of patients have a rapidly fulminating course leading to death in only a few months. The emergence of new diagnostic techniques and our increasing diagnostic acumen may reveal in the future that what we now call MS may represent only the tip of an iceberg and that there may be a huge number of benign monosymptomatic or asymptomatic cases in the population at large which are as yet undiagnosed or not diagnosable.
It should again be emphasized that results of cerebrospinal fluid (CSF) studies and other test may be abnormal for various reasons; hence, these are not specific for MS.
A 36 year-old laborer, bom and raised in Brazil, has been living in Southern Louisiana for the past two years working as a fisherman. Over the past several months he has been developing a gradually progressive weakness and numbness of both lower extremities, problems with balance and coordination, and urinary retention. On neurological examination you find increased DTR's 3+ in upper extremities and 4+ in lower extremities with ankle clonus and bilateral Hoffman reflex and Babinski. Cranial nerves are normal.
A 57 year-old Caucasian female house wife, obese, known hypertensive, and insulin dependent diabetic for the past 15 years, has developed weakness and numbness in the lower extremities over the past several months. The primary care physician has obtained a MRI of the brain without Gadolinium contrast. The radiology report indicates that on the T-2 weighted images there are "few punctate lesions bilaterally in the supratentorial white matter, at the subcortical level and in the basal ganglia bilaterally, compatible with the diagnosis of multiple sclerosis". The primary care physician, during a casual conversation in the cafeteria, requests your opinion on the case without giving you any details on the neurologic examination and wants to know which other diagnosis tests you would request.
A 32 year-old female, bom and raised in Fargo, ND, who has been working in New Orleans for the past three years as a sales manager in a Department store, has a history of having had a right optic neuropathy seven years ago with complete recovery of function without any treatment. Four years ago she experienced a foot drop on the left treated as a common peroneal palsy and improved after treatment by a chiropractor. A few months ago she developed urinary incontinence and right-sided hemiparesis without speech or language impairment. The only diagnostic test obtained was a CT scan of the brain, which was reported as normal and was put on two week course of oral prednisone, 60 mg daily, followed by 20 mg daily for the past three months and has experienced partial improvement. She has put on more than 20 lbs and has recently been found out to have type II diabetes. She was never seen by a neurologist but has been seeing a psychologist for marital problems, and at the suggestion of her psychologist she comes to you for assessment and appropriate diagnostic and therapeutic management.
Tulane University, New Orleans, LA 70118 504-865-5000 firstname.lastname@example.org